There are a variety of types of cassettes for storing disks, such as disks that are coated with magnetic recording material or laser recordable material for storing data, audio information, video information, and the like. Some cassettes are specifically designed for use in automated transfer systems. For example, a cassette may be used to transfer magnetic disks ("hard disks") from one station of an automated system to another station. Other cassettes are designed for shipping disks from one facility to another.
An example of a cassette for handling disks is shown in FIG. 1. The cassette 10 includes opposed lengthwise walls 12 and 14 and opposed widthwise walls 16 and 18. Projections 20 along the interior circumference of the lengthwise walls form slots 22. Disks, such as magnetic recording disks, are retained in parallel spaced-apart relation by the projections 20. A cassette lid 24 includes a pair of downwardly depending flaps 26 and 28. The configuration of the flaps and the widthwise walls 16 and 18 of the cassette 10 allow the lid to be fastened to the cassette. Typically, the lid is snap-fit to the cassette, but a friction-fit may be substituted. Optionally, the cassette may have a bottom cover that is removable to expose the lower edges of the stored disks. Thus, an elevator blade may extend upwardly through the cassette to individually lift disks to and from the cassette.
While cassettes operate well for their intended purposes, there are concerns relating to use of the cassettes. In a single working shift, a person within a fabrication area may be required to manually seat and unseat a number of lids from cassettes. In the example cassette 10 of FIG. 1, the cassette lid 24 is securely fit to the cassette 10 in order to minimize the risk of the lid inadvertently being removed when disks within the cassette may be exposed to an "unclean" area. Particles that settle on a magnetic disk or semiconductor wafer will negatively impact manufacturing yields. A secure fit is assured by forming the lid of a pliable material that has a strong material memory. That is, the flaps may be deformed outwardly by applying sufficient force at the bottom of the flaps, but the cassette lid will return to its original condition when the outward force is removed. Thus, the flaps snap onto the widthwise walls 16 and 18 of the cassette. One concern is that the repetitive seating and unseating of cassette lids may cause prolonged stress pains to the body of the fabrication personnel. A significant force must be applied to the lid in order to deform the lid. Another concern is that the seating and unseating of lids will cause particle generation. Even though the cassettes and cassette lids are formed of low or non-particulating material, minute particles may be generated as the flaps forcibly slide into and out of position.
An automated seating and unseating apparatus is described in U.S. Pat. No. 5,657,617 to Allen et al. The apparatus utilizes pneumatic pressure to mechanically remove a cassette lid. Fingers are moved downwardly from above the cassette to a position adjacent to the bottoms of the flaps to be removed. The fingers are then shifted into a position to apply outward force to the flaps. The outward force deforms the lid, allowing the apparatus to be moved upwardly. After the lid is sufficiently high to clear the cassette, the cassette is repositioned or the disks are removed from the cassette.
The automated apparatus of Allen et al. operates well for a mass production area that includes the necessary electrical and pneumatic utilities. However, the apparatus is not well suited for applications that require portability and applications in which the required utilities are not available. What is needed is a stand-alone device and method for seating and unseating cassette lids from cassettes. What is further needed is such a method and device that do not impose significant bodily stress on an operator and do not generate contamination particles during operation.